Ultrasonographic findings of the normal diaphragm: thickness and contractility

Abstract

Background Neuromuscular ultrasound can be used to assess the diaphragm. Before it can be used clinically, the reference ranges of diaphragm thickness and contractility must be determined. Methods We measured the thickness of the diaphragm and the diaphragmatic thickening fraction (DTF) in 80 healthy volunteers with ultrasound and collected their demographic infor-mation to determine if age, sex, and body mass index (BMI) influence these measures. Results The thickness of the diaphragm at resting end expiration was 0.193 ± 0.044 cm on the right side and 0.187 ± 0.039 cm on the left. The DTF was 104.8 ± 50.6% on the right side and 114.9 ± 49.2% on the left. Sex, weight, height, and BMI significantly affected the thickness of the diaphragm, but had little effect on the DTF. Conclusions Normal reference values for the diaphragm should be helpful when evaluating the diaphragm. The DTF appears more useful than resting diaphragm thickness because it is affected less by individual variation.